The present invention relates generally to trailer and front wheel drive self-propelled vehicle bed moving apparatus, and more particularly to trailer bed lifting and tilting apparatus for changing the bed position from its traveling position within a movable frame to a position where it can easily be loaded or unloaded without having to tilt the frame which carries the bed or detach the frame from means for providing motion thereto.
The loading and unloading of trailers with fixed beds often requires that the trailer be detached from its hauling vehicle in order that the trailer may be tilted until the rear of the bed reaches the ground. Alternatively, a ramp may be used to bridge the gap between the horizontal, off the ground trailer and bed, and the ground. More complicated trailer designs include beds which can be displaced relative to their supporting frames. A simple design might include a bed pivoted at the rear of the frame with the front of the bed reversibly attached near the front of the frame. The frame, with the bed attached would then be tilted rearward until the rear of the bed rests on the ground, the front of the bed then detached from the frame and lowered using a winch, for example, until it reaches the ground, whereby the entire bed is situated on the ground with the rear of the trailer frame touching the ground, from which position the trailer may be loaded. The reverse procedure would return the loaded trailer to its horizontal position. A variation on this latter design is disclosed in U.S. Pat. No. 4,077,643 for "Drop Frame Trailer," issued to Dean E. Bates on Mar. 7, 1978. By employing a U-shaped axle which attaches the frame to a wheel suspension system which can be raised or lowered by rotation of the wheel suspension about this axle, however, the Bates invention allows the rear of the trailer frame to be raised from, or lowered to the ground without requiring that the trailer frame be detached from its driving vehicle. The front of the trailer frame can also then be raised or lowered without detaching the frame from its pulling vehicle. It would be desirable, however, to be able to place the trailer bed in its horizontal position in contact with the ground in a single lowering step. Moreover, occasions can be envisioned where it would be advantageous to maintain the bed in a horizontal attitude during the entire loading and unloading preocess. Neither of these objectives could be attained utilizing the Bates design.
A more complicated design for a trailer with a lowerable bed is disclosed in U.S. Pat. No. 4,109,811, "Trailer With Lowerable Bed," issued to James L. Stucky on Aug. 29, 1978. Therein, the bed of the trailer is pulled forward to a position whereby it first tilts the guiding structure upon which it is slidably located about a previously locked, wheeled transverse axle structure, which supports the guiding members and the bed, until the guiding members touch the ground, and then it is pulled further forward until the rear of the bed is stopped by the guiding members in front of the axle structure, but with the rear of the bed still maintaining contact with the guiding structure so that the process can be reversed once the trailer bed is loaded. The front of the bed can now be lowered from the hauling vehicle to permit the bed to come to a substantially horizontal position as may be required for loading and unloading. A similar pivoting track sliding arrangement operating in essentially the same way as Stucky' trailer is described in U.S. Pat. No. 4,318,656, "Equipment Trailer With Shiftable Trailer Bed," issued to Charles R. Ezell on Mar. 9, 1982. The principal difference between the two trailers appears to lie in the manner in which the bed guiding members pivot about the trailer wheels. it is important to recognize that some form of external hauling vehicle or apparatus is required to displace the trailer bed from the transporting wheeled axle structure in both the Stucky and the Ezell trailer designs since there are no disclosed trailer frame members surrounding the trailer bed which may be used to assist in moving the bed relative to the axle structure without the assistance of a device external to the trailer for supplying the required force. Moreover, a significant forward motion of the bed is required to achieve its horizontal position on the ground, and the hauling vehicle may have to be detached from the front of the trailer bed in order to load cargo which cannot be loaded from the side.
Accordingly, it is an object of the present invention to provide an apparatus for substantially horizontally raising and lowering a trailer bed for loading and unloading the bed in a single step without having to detach the draft vehicle.
Another object of the present invention is to provide an apparatus having the capability of also tilting the trailer bed for ease of unloading in some instances in addition to the horizontal raising and lowering capability thereof.
Yet another object of the present invention is to permit the raising and lowering of the trailer bed without the necessity of a hauling apparatus external to the trailer.
Still another object of my invention is to permit the raising and lowering of the trailer bed and the tilting thereof in a small horizontal distance rearward relative to the initial location of the trailer bed.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.